While shelled nuts retain helpful levels of oleic acids in their oil, the oil can turn rancid in nuts that are packaged too long. I personally like eating nuts fresh from the shell -- even though nut-cracking is time consuming.

2. Fish with Omega-3 Fatty Acids

I like a lunch that makes me feel alert rather than sleepy. So, often I open a can of wild-caught Alaskan red salmon to have with a salad. (Pink salmon will do, if red is too expensive). If you buy small 4 oz. packets or cans with pull tops, salmon becomes an easily portable and convenient meal.

This fish and other wild, cold-water varieties benefit the brain because the oils and protein in the fish enable the brain to build better nerve connections, allowing people to concentrate better.

Researchers at the Brain Institute affirmed these claims in a study, finding that lab animals fed with fish completed complex tasks 66 percent faster than animals fed carbs. That's a convincing argument to avoid doughnuts and potato chips when you're on your work break!